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digitalmars.D.bugs - problem with inheritance of FilterStream

reply bayo <bayo.fr gmail.com> writes:
Hello.

Iv got a problem today i never seen befor. Maybe its the first time i
inherite a phobos class, i realy dont know.

When i create instance of Foo, the printf (maybe) generate an
"Error: Access Violation". If i remove all printf of the class (my real 
class is not this simple example) it run (but its hard to debug).

To "patch" this problem i remove the FilterStream inheritance, but i
use the same interface (without a real interface). I can do it for the
moment, but its not fine at all.

I have this problem with dmd 1.013 (win), i update to 1.015 and
its the same. I compile with -unittest, i test without this option,
and it change nothing.

I spend long time to understand the problem, is anybody see it?


import std.stream;

class Foo : FilterStream {
	this (Stream stream) {
		printf("foo\n"); // Error: Access Violation
		super(stream);
	}
}

class Foo2 {
	Stream source;
	this (Stream stream) {
		printf("foo2\n"); // No problem
		source = stream;
	}
}

unittest {
	printf("begin\n");
	new Foo(null);
	printf("end\n");
}

Thanks a lot for your help.
--bayo
Dec 30 2007
parent reply Derek Parnell <derek psych.ward> writes:
On Sun, 30 Dec 2007 17:52:41 +0100, bayo wrote:


 Hello.
 
 Iv got a problem today i never seen befor. Maybe its the first time i
 inherite a phobos class, i realy dont know.
 
 When i create instance of Foo, the printf (maybe) generate an
 "Error: Access Violation". 


This is the problem. It is using the wrong 'printf'. The code below works.

 
 import std.stream;
 import std.stdio;

 class Foo : FilterStream {
 	this (Stream stream) {
 		std.stdio.printf("foo\n");
 		super(stream);
 	}
 }
 
 unittest {
 	printf("begin\n");
 	new Foo(null);
 	printf("end\n");
 }

-- 
Derek Parnell
Melbourne, Australia
skype: derek.j.parnell
Dec 30 2007
parent reply Derek Parnell <derek nomail.afraid.org> writes:
Actually, if I was doing this I'd write it more like ...

 import std.stream;
 import std.stdio : dbg = writefln;

 
 class Foo : FilterStream {
 	this (Stream stream) {
 		debug dbg("foo");
 		super(stream);
 	}
 }
 
 unittest {
 	debug dbg("begin");
 	new Foo(null);
 	debug dbg("end");
 }

 void main(){}

-- 
Derek
(skype: derek.j.parnell)
Melbourne, Australia
31/12/2007 9:16:36 AM
Dec 30 2007
parent bayo <bayo.fr gmail.com> writes:
Derek Parnell a écrit :

 Actually, if I was doing this I'd write it more like ...
 
  [...]


Thanks a lot for your help Derek. I think i will do it now,
it an easily method to prevent this king of error.

--bayo
Dec 31 2007